In an Internet Protocol (IP) network, every host computer is assigned an IP address for identifying the host computer communications over the network. Today, in 2009, the vast majority of computers on the Internet are compatible with Internet Protocol version 4 (IPv4) which utilizes a dotted decimal format IP address field. The IPv4 address contains four numbers, each ranging from 0 to 255 (e.g. 10.1.322.65) which provide a maximum of 4,294,967,296 possible addresses. Over the past several decades, the world has witnessed a sharp increase of host computers on the Internet, including an explosion in the number of Internet connected wireless mobile devices. As a result, a depletion of unassigned IPv4 addresses available for use by new hosts has reached a critical level. This problem, commonly referred to as IPv4 address exhaustion, has been taking place in the global IPv4 address pool as well as in the IPv4 address pools assigned to regional registries around the globe.
Approximately 15 years ago, the Internet Engineering Task Force (IETF) began developing IPv6 as the intended successor to IPv4. Finalized in 1996, the new IPv6 standard provides approximately 3.4×1038 addresses, which are 7.9×1028 times as many addresses provided for by the IPv4 standard. While having developed IPv6, in part, to alleviate the IPv4 address exhaustion problem, the Internet community recognized that the deployment of IPv6 enabled equipment and services would take place over an extended duration and that IPv4 would remain active for many years and decades to come, needing to coexist with IPv6 until the Internet arrived at IPv6 parity with IPv4.
Accordingly, other technologies have emerged to help mitigate the problem of IPv4 address exhaustion. Notably, network address translation (NAT) has been successfully used for many years in which multiple hosts on a private network share a single IPv4 IP address on the public Internet. Using NAT, hosts on a private network behind a NAT device each have a private IP address that is only used on the private network. When one of these hosts transmits packets outside of the private network, the NAT device modifies the packets to replace the host's private IP address with a public IP address. The public IP address is shared by the entire private network such that the packets appear to come from the NAT device itself. In reply to these outbound packets with the public IP address, packets received from the public Internet will likewise be addressed to the shared public IP address. The NAT device keeps track of which host originally transmitted outbound packets to form an address mapping so that inbound packets can be reverse translated, replacing the public IP address with the correct corresponding private IP address. The NAT device then forwards the translated inbound packets to the correct host. NAT devices are often implemented in a network gateway, which is a device typically used in home networking scenarios where multiple subscriber computers are connecting to the Internet. Network gateways are sometimes referred to as home gateways. Network gateways of today most often use NAT for IPv4 to enable Internet or network connectivity, but in the future, network gateways or routers will need to support IPv6 networking which is not analogous or compatible with the current IPv4 NAT functionality.
At present, the Internet community is finding itself in a difficult situation given that technologies such as NAT are quickly becoming insufficient in dealing with the dwindling number of available public IPv4 addresses, and for a variety of reasons, the adoption rate of the IPv6 standard has been slow to the point that IPv6 capable equipment is not widely developed or deployed. Compounding the problem is the absence of content and services over IPv6. So even if a substantial quantity of Internet users were to suddenly find themselves with IPv6 Internet access, there is currently little to no IPv6 content or services for this population to consume. Thus, there is little incentive for consumers to purchase next generation equipment such as network gateways that could support advanced simultaneous IPv4 and IPv6 connectivity.